The goal of the proposed research is to characterize the natural genetic and transcriptional variation contributing to variation in resistance to oxidative stress in the model organism, Drosophila melanogaster. Oxidative stress is involved in susceptibility to many complex human diseases such as cardiovascular and neurodegenerative diseases. To date, research of oxidative stress in Drosophila has been largely limited to a few inbred lines, large numbers of natural isolates have not been assessed. This research proposal has three main goals. First, to characterize natural genetic variation contributing to variation in resistance to oxidative stress induced via three mechanisms in 192 wild-derived isofemale lines using genome-wide association mapping with whole genome sequence data from each line. Second, to identify genetic networks associated with resistance to oxidative stress by regressing this trait onto whole genome expression profiles. Third, to perform functional studies to confirm associations of interest and validate networks using mutant analysis and QTL mapping in an advanced intercross outbred population. Drosophila represents a unique system where large numbers of natural isolates can be reared to provide the statistical power needed to detect variants of small effect. Also, the method of induction of oxidative stress can be controlled and resistance quickly assayed. Most importantly Drosophila has a wide variety of molecular tools that can be used to validate the associations detected. The genetic architecture of resistance to oxidative stress has important implications for many complex diseases and could possible suggest new targets for therapeutic methods if human orthologues are confirmed. The genetic networks associated with resistance to oxidative stress detected by this analysis could also lead to new therapeutic targets. Lastly, by assaying resistance to oxidative stress on these 192 lines that constitute the Drosophila Genetic Reference Panel (DGRP), a community resource, it will provide the opportunity to assess the pleiotropic nature of this genetic and transcriptional architecture once other traits are assayed on this same population. This research proposes to investigate the genetic variation that contributes to variation in resistance to reactive oxygen species, otherwise known as oxidative stress, in the model organism Drosophila melanogaster (fruit flies). This analysis will result in the identification genes and genetic networks that control resistance to oxidative stress which is involved in susceptibility to many human diseases such as cardiovascular disease and neurodegenerative diseases.